An object is, in a thin film transistor in which an oxide semiconductor is used as an active layer, to prevent change in composition, film quality, an interface, or the like of an oxide semiconductor region serving as an active layer, and to stabilize electrical characteristics of the thin film transistor. In a thin film transistor in which a first oxide semiconductor region is used as an active layer, a second oxide semiconductor region having lower electrical conductivity than the first oxide semiconductor region is formed between the first oxide semiconductor region and a protective insulating layer for the thin film transistor, whereby the second oxide semiconductor region serves as a protective layer for the first oxide semiconductor region; thus, change in composition or deterioration in film quality of the first oxide semiconductor region can be prevented, and electrical characteristics of the thin film transistor can be stabilized.
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1. A method for manufacturing a semiconductor device comprising: forming a gate electrode over a substrate; forming a gate insulating layer over the gate electrode; forming a conductive film over the gate insulating layer; etching the conductive film to form a source electrode and a drain electrode; forming a first oxide semiconductor film over the gate insulating layer, the source electrode and the drain electrode by a sputtering method; forming a second oxide semiconductor film over the first oxide semiconductor film by a sputtering method; forming a mask over the second oxide semiconductor film; and etching the first oxide semiconductor film and the second oxide semiconductor film by using the mask to form a first oxide semiconductor region and a second oxide semiconductor region, wherein the first oxide semiconductor region is provided so that part of the first oxide semiconductor region is in contact with the gate insulating layer and side surface portions of the source electrode and the drain electrode, wherein a proportion of a flow rate of an oxygen gas in a film-forming gas for forming the second oxide semiconductor film is made higher than a proportion of a flow rate of an oxygen gas in a film-forming gas for forming the first oxide semiconductor film, and wherein a concentration of sodium in the first oxide semiconductor film is 5×10 19 /cm 3 or lower.
A method for manufacturing a semiconductor device involves these steps: First, a gate electrode is formed on a substrate, followed by a gate insulating layer on top of the gate electrode. Next, a conductive film is deposited and etched to create source and drain electrodes. Then, a first oxide semiconductor film is formed over the gate insulating layer, source electrode, and drain electrode using sputtering. A second oxide semiconductor film is then formed on top of the first, also by sputtering. A mask is applied, and both oxide semiconductor films are etched to create the first and second oxide semiconductor regions. The first oxide semiconductor region contacts the gate insulating layer and the sides of the source/drain electrodes. The oxygen gas flow rate is higher during the deposition of the second oxide semiconductor film than during the first. Crucially, the sodium concentration in the first oxide semiconductor film is kept at or below 5 x 10^19 /cm^3.
2. The method for manufacturing a semiconductor device according to claim 1 , wherein each of the first oxide semiconductor film and the second oxide semiconductor film contains at least one of indium, gallium, zinc, and tin.
This manufacturing method builds upon the previous semiconductor fabrication process where a gate electrode and insulating layer are formed followed by source/drain electrodes. First and second oxide semiconductor films are deposited, masked, and etched to form corresponding semiconductor regions. The oxygen gas flow rate is higher during the second film's deposition, and the first film's sodium concentration is low. Both the first and second oxide semiconductor films contain at least one of these elements: indium, gallium, zinc, or tin. This indicates the use of an IGZO or similar material system for the active semiconductor layers.
3. The method for manufacturing a semiconductor device according to claim 1 , wherein the first oxide semiconductor film and the second oxide semiconductor film are formed in one step by increasing the flow rate of the oxygen gas.
This method enhances a semiconductor fabrication process involving the formation of a gate electrode and insulating layer, source/drain electrodes, and first and second oxide semiconductor films which are etched to form semiconductor regions. The oxygen gas flow rate is higher during the second film's deposition and the first film has low sodium content. The first and second oxide semiconductor films are formed in a single, continuous sputtering step, where the flow rate of oxygen gas is increased mid-deposition to transition from the first to the second oxide semiconductor film's composition.
4. The method for manufacturing a semiconductor device according to claim 1 , wherein the proportion of the flow rate of the oxygen gas in the film-forming gas for forming the first oxide semiconductor film is lower than 70 volume %, and wherein the proportion of the flow rate of the oxygen gas in the film-forming gas for forming the second oxide semiconductor film is 70 volume % or higher.
This semiconductor manufacturing method follows the sequence of forming a gate electrode, gate insulating layer, source/drain electrodes, first and second oxide semiconductor films, masking, and etching to create oxide semiconductor regions. A key aspect involves controlling the oxygen gas flow during film deposition. The oxygen gas flow rate for forming the first oxide semiconductor film is below 70 volume percent. The oxygen gas flow rate for forming the second oxide semiconductor film is 70 volume percent or higher. Also, the sodium concentration in the first oxide semiconductor film is limited.
5. A method for manufacturing a semiconductor device comprising: forming a gate electrode over a substrate; forming a gate insulating layer over the gate electrode; forming a first oxide semiconductor film over the gate insulating layer by a sputtering method; forming a second oxide semiconductor film over the first oxide semiconductor film by a sputtering method; forming a mask over the second oxide semiconductor film; and etching the first oxide semiconductor film and the second oxide semiconductor film by using the mask to form a first oxide semiconductor region and a second oxide semiconductor region, wherein a proportion of a flow rate of an oxygen gas in a film-forming gas for forming the second oxide semiconductor film is made higher than a proportion of a flow rate of an oxygen gas in a film-forming gas for forming the first oxide semiconductor film, and wherein a concentration of sodium in the first oxide semiconductor film is 5×10 19 /cm 3 or lower.
A method for manufacturing a semiconductor device involves these steps: First, a gate electrode is formed on a substrate, followed by a gate insulating layer on top of the gate electrode. Then, a first oxide semiconductor film is formed over the gate insulating layer using sputtering. A second oxide semiconductor film is then formed on top of the first, also by sputtering. A mask is applied, and both oxide semiconductor films are etched to create the first and second oxide semiconductor regions. The oxygen gas flow rate is higher during the deposition of the second oxide semiconductor film than during the first. Crucially, the sodium concentration in the first oxide semiconductor film is kept at or below 5 x 10^19 /cm^3.
6. The method for manufacturing a semiconductor device according to claim 5 , wherein each of the first oxide semiconductor film and the second oxide semiconductor film contains at least one of indium, gallium, zinc, and tin.
The semiconductor fabrication process described previously involves forming a gate electrode and insulating layer and then depositing first and second oxide semiconductor films that are masked and etched. The oxygen flow rate is higher when forming the second film, and the first film's sodium concentration is low. In this variation, both the first and second oxide semiconductor films contain at least one of these elements: indium, gallium, zinc, or tin. This implies the use of materials like IGZO for the semiconductor layers.
7. The method for manufacturing a semiconductor device according to claim 5 , wherein the first oxide semiconductor film and the second oxide semiconductor film are formed in one step by increasing the flow rate of the oxygen gas.
A semiconductor manufacturing method outlines the steps of forming a gate electrode, a gate insulating layer, a first oxide semiconductor film, and a second oxide semiconductor film, which are subsequently masked and etched. The rate of oxygen gas flow is higher when forming the second oxide film, and the sodium concentration of the first film is kept low. This version forms the first and second oxide semiconductor films in a single, continuous sputtering step by increasing the flow rate of the oxygen gas during the film deposition to transition from the first film's composition to the second film's.
8. The method for manufacturing a semiconductor device according to claim 5 , wherein the proportion of the flow rate of the oxygen gas in the film-forming gas for forming the first oxide semiconductor film is lower than 70 volume %, and wherein the proportion of the flow rate of the oxygen gas in the film-forming gas for forming the second oxide semiconductor film is 70 volume % or higher.
Building upon the method of fabricating a semiconductor device, including steps such as forming a gate electrode, a gate insulating layer, first and second oxide semiconductor films, and etching, this claim specifies oxygen flow rate percentages. The oxygen gas flow rate for the first oxide semiconductor film is less than 70 volume percent. The oxygen gas flow rate for the second oxide semiconductor film is 70 volume percent or higher. In addition, the sodium concentration in the first oxide semiconductor film is controlled.
9. A method of manufacturing a semiconductor device comprising the steps of: forming a gate insulating film over a gate electrode; forming a first non-single crystalline oxide semiconductor film comprising indium over the gate electrode with the gate insulating film interposed therebetween, the first non-single crystalline oxide semiconductor film having a first conductivity; and forming a second non-single crystalline oxide semiconductor film comprising indium over the first non-single crystalline oxide semiconductor film, the second non-single crystalline oxide semiconductor film having a second conductivity lower than the first conductivity, wherein outer side edges of the first non-single crystalline oxide semiconductor film are coextensive with outer side edges of the second non-single crystalline oxide semiconductor film, wherein at least a portion of the first non-single crystalline oxide semiconductor film functions as a channel formation region, wherein the second non-single crystalline oxide semiconductor film overlaps the portion of the first non-single crystalline oxide semiconductor layer, and wherein a concentration of sodium in the oxide semiconductor film is 5×10 19 /cm 3 or lower.
A method for creating a semiconductor device involves forming a gate insulating film over a gate electrode. A first non-single crystalline oxide semiconductor film containing indium is deposited over the gate electrode, separated by the insulating film; this film has a first conductivity. A second non-single crystalline oxide semiconductor film with indium is deposited on top of the first; this film has a second conductivity, which is lower than the first. The outer edges of both oxide semiconductor films align. At least part of the first oxide semiconductor film acts as a channel. The second oxide semiconductor film overlaps this channel region. The concentration of sodium in the oxide semiconductor film is 5×10^19 /cm^3 or lower.
10. The method according to claim 9 , wherein each of the first non-single crystalline oxide semiconductor film and the second non-single crystalline oxide semiconductor film further comprises gallium and zinc.
The method for manufacturing a semiconductor device, which includes forming gate insulation, and first/second indium-containing non-single crystalline oxide semiconductor films with different conductivities, also specifies the material composition. Both the first and second non-single crystalline oxide semiconductor films also include gallium and zinc. This means that the oxide semiconductor films are likely IGZO (Indium Gallium Zinc Oxide).
11. The method according to claim 9 , wherein a thickness of the first non-single crystalline oxide semiconductor film is 10 nm to 300 nm.
This method, which manufactures a semiconductor device by forming a gate insulating film over a gate electrode and depositing first and second indium-containing non-single crystalline oxide semiconductor films with different conductivities, specifies a thickness for the first semiconductor film. The thickness of the first non-single crystalline oxide semiconductor film is between 10 nm and 300 nm.
12. The method according to claim 5 , wherein the first oxide semiconductor region is provided so that part of the first oxide semiconductor region is in contact with the gate insulating layer.
The manufacturing method for creating a semiconductor device including forming a gate electrode, gate insulating layer, first and second oxide semiconductor films, and etching processes, further specifies the positioning of the first oxide semiconductor region. Specifically, part of the first oxide semiconductor region makes direct contact with the gate insulating layer.
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October 2, 2013
August 1, 2017
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